UA astronomers will watch for Lunar Prospector plume Saturday -- and wish Gene Shoemaker a final happy landing

July 28, 1999


Carolyn C. Porco

Stephen M. Larson

Ann L. Sprague

TUCSON, ARIZ. -- When Lunar Prospector crash dives into the moon_s south
pole early Saturday morning, Tucson-based observers hope for clear skies and
a good view.

Also watching intently will be a University of Arizona planetary scientist
who is sending a memorial tribute aboard the satellite.

UA astronomers and others observing near Tucson are part of an extensive
network that will be searching for water vapor in Lunar Prospector_s impact

Since its launch in January 1998, Lunar Prospector has scored a number of
scientific coups, as well as a followup confirmation of possible water-ice
deposits at the north and south lunar poles. The question is whether the
hydrogen it detected exists in water ice or in hydrogen-containing compounds
called hydrates. Not all scientists agree this experiment will definitively
answer the question. (For more on that, see news online at > )

However, the answer is of scientific and practical interest for future space
explorers. Sending a pint of water to the moon costs $10,000. So picking it
up at the south lunar pole could turn out to be one of the biggest bargains
in this part of the solar system.

Aerospace engineers at the University of Texas in Austin were the first to
conceive of crashing Lunar Prospector into a frigid, shadowed crater at the
lunar south pole just before the satellite runs out of fuel. The 354-pound
(161 kg) Lunar Prospector will be traveling at 3,600 mph (5,793 kph) or
faster. If the impact plume it generates is large enough _ and that_s a big
"if," scientists emphasize _ observers might discover the first irrefutable
proof of water on the moon. But scientists caution that it may take weeks or
months of data crunching before this is confirmed.

The project was approved by officials at the NASA Ames Research Center in
Moffett Field, Calif., which manages the mission, and at NASA Headquarters
in Washington, D.C. Observers will watch for the impact plume with
telescopes at several locations including Texas, California, and Hawaii.
Those involved will include the Hubble Space Telescope, the Keck 1
telescope, and the MacDonald Observatory telescopes.

If monsoon clouds don_t obscure their views. Ann L. Sprague and Stephen M.
Larson, both of the UA Lunar and Planetary Laboratory (LPL), will observe
with telescopes in the Santa Catalina Mountains north of Tucson. Other
astronomers will use the McMath-Pierce and WIYN telescopes on Kitt Peak,
southwest of Tucson.

Sprague and her colleagues will use the UA_s 1.54 meter (61-inch) telescope
on Mount Bigelow to monitor sodium in the moon_s diaphanous atmosphere
before, during and after impact. They are trying to learn more about the
structures of the thin atmospheres on the moon and planet Mercury by using
spectroscopy to look for sodium and other elements..

Larson will install special filters on the 1.52 -meter (60-inch) NASA
reflector telescope on Mount Lemmon to look for OH, a byproduct of water.
"Given the moon_s low declination and the monsoon weather, I don_t expect
anything close to Keck or HST results, but I_ll be looking anyway," he said.

The 61-inch telescope was built by the late Gerard Kuiper, who founded LPL,
in the early 1960s to survey the moon in preparation for the lunar
spacecraft missions being proposed at that time. Kuiper died in 1973. His
ashes were placed at the 61-inch telescope during a small LPL celebration
last month. The Mount Lemmon 60-inch telescope, also built by Kuiper, was
used for lunar laser ranging observations after Apollo 11.


The filters Larson will use are the same ones he used in photographing Comet
Hale-Bopp from Tucson in April 1997. One of those images rides on a small,
polycarbonate capsule that is hitching a ride to the moon aboard Lunar
Prospector. The capsule is wrapped in a piece of brass foil inscribed with
Larson_s image of Comet Hale-Bopp, an image of Meteor Crater in northern
Arizona and a passage from Shakespeare_s "Romeo and Juliet."

Inside the capsule are the ashes of the late Eugene M. Shoemaker. Shoemaker
was a pioneering planetary geologist famous for his work on extraterrestrial
impacts and for his later collaboration with his wife, Carolyn, in the study
and discovery of comets. He was killed in a July 1997 auto accident in
Australia. LPL Associate Professor Carolyn C. Porco conceived, designed and
produced this tribute honoring Shoemaker in time for the Lunar Prospector
launch only months after Shoemaker_s death.

"It was legend among planetary scientists that Gene_s life-long dream was to
go to the moon and study its geology firsthand," Porco said. "At his
journey_s end _ thirty years to the month after humans first set foot on the
moon _ Eugene M. Shoemaker will become the first inhabitant of Earth to be
sent to rest on another celestial body," Porco said.

Porco has produced replicas of the Shoemaker tribute foil for museum
display. They have been sent to the Smithsonian Air and Space Museum in
Washington, D.C.; the Adler Planetarium in Chicago, the Hayden Planetarium
in New York and the U.S. Geological Survey headquarters in Reston, Va.,

Copies also have been given to the U.S. Geological Survey Gene Shoemaker
Building, which is under construction in Flagstaff, Ariz.; the Meteor Crater
Visitor Center; NASA Ames Research Center; NASA Headquarters; and the UA
Lunar and Planetary Laboratory.

Additional copies have gone to Carolyn Shoemaker; NASA Chief Administrator
Dan Goldin; Wesley Huntress, formerly head of the NASA Space Sciences
Division; and Bruce Babbitt, U.S. Secretary of the Interior.

For more information on the Shoemaker tribute, see the UA News Services
release of Jan. 6, 1998, "Lunar spacecraft carries ashes, special tribute to
Shoemaker," at
View the tribute online at >

Larson's Comet Hale-Bopp image is available by FTP to host server with anonymous login (email as password).

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